Lubricating oil compositions used to lubricate internal combustion engines contain a base oil of lubricating viscosity, or a mixture of such oils, and additives used to improve the performance characteristics of the oil. For example, additives are used to improve detergency, to reduce engine wear, to provide stability against heat and oxidation, to reduce oil consumption, to inhibit corrosion, to act as a dispersant, and to reduce friction loss. Some additives provide multiple benefits, such as dispersant-viscosity modifiers. Other additives, while improving one characteristic of the lubricating oil, have an adverse effect on other characteristics. Thus, to provide lubricating oil having optimal overall performance, it is necessary to characterize and understand all the effects of the various additives available, and carefully balance the additive content of the lubricant.
Despite the foregoing, there continues to be a need for more cost effective lubricant compositions that provide equivalent or superior performance with respect to sludge formation reduction.
In accordance with a first aspect, one exemplary embodiment of the disclosure provides an improved lubricating oil composition that may provide equivalent or superior lubricating properties. The fully formulated lubricating oil composition has therein at least one succinimide dispersant, a metal containing detergent, at least one antioxidant, and a hydrocarbon soluble titanium compound. The lubricating oil has improved sludge reducing properties compared to the same lubricating oil composition devoid of the titanium compound.
In accordance with a second aspect, the disclosure provides a lubricant additive concentrate for reducing sludge in a lubricant composition. The additive concentrate contains a hydrocarbyl carrier fluid, at least one succinimide dispersant, at least one friction modifier, and a hydrocarbon soluble titanium compound providing from about 10 to about 1000 ppm titanium to the lubricant composition sufficient to reduce sludge formation during use of the lubricant composition to a level less than a level of sludge formation formed during use of the lubricant composition devoid of the titanium compound.
In accordance with a third aspect, the disclosure provides a lubricated surface having a lubricant composition containing a base oil of lubricating viscosity and an additive package in contact therewith. The additive package includes at least one succinimide dispersant, a metal containing detergent, at least one wear reducing agent, at least one antioxidant, and a hydrocarbon soluble titanium compound. The lubricant composition has improved sludge reducing properties compared to the same lubricant composition devoid of the titanium compound.
Yet another aspect of the disclosure provides a fully formulated lubricant composition including a base oil component of lubricating viscosity and an amount of sludge reducing lubricant additive. The lubricant additive contains at least one succinimide dispersant, a metal containing detergent, at least one antioxidant, and a hydrocarbon soluble titanium compound as a friction modifier providing from about 10 to about 500 ppm titanium to the lubricant composition.
An advantage of the disclosed embodiments is a significant improvement in sludge reduction over compositions containing titanium compounds and conventional succinimide dispersants. The foregoing advantage is obtained despite the absence of molybdenum containing compounds in the lubricant composition. Other and further objects, advantages and features of the disclosed embodiments may be understood by reference to the following.